package org.rsbot.util;
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.math.BigInteger;

/**
 * Provides Base64 encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
 * <p/>
 * <p>
 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
 * </p>
 * <p>
 * The class can be parameterized in the following manner with various constructors:
 * <ul>
 * <li>URL-safe mode: Default off.</li>
 * <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of
 * 4 in the encoded data.
 * <li>Line separator: Default is CRLF ("\r\n")</li>
 * </ul>
 * </p>
 * <p>
 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
 * </p>
 * <p>
 * This class is not thread-safe. Each thread should use its own instance.
 * </p>
 *
 * @author Apache Software Foundation
 * @version $Revision$
 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
 * @since 1.0
 */
public class Base64 {

	/**
	 * MIME chunk size per RFC 2045 section 6.8.
	 * <p/>
	 * <p>
	 * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
	 * equal signs.
	 * </p>
	 *
	 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
	 */
	public static final int MIME_CHUNK_SIZE = 76;

	/**
	 * PEM chunk size per RFC 1421 section 4.3.2.4.
	 * <p/>
	 * <p>
	 * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
	 * equal signs.
	 * </p>
	 *
	 * @see <a href="http://tools.ietf.org/html/rfc1421">RFC 1421 section 4.3.2.4</a>
	 */
	public static final int PEM_CHUNK_SIZE = 64;

	private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;

	/**
	 * Defines the default buffer size - currently {@value}
	 * - must be large enough for at least one encoded block+separator
	 */
	private static final int DEFAULT_BUFFER_SIZE = 8192;

	/**
	 * Mask used to extract 8 bits, used in decoding bytes
	 */
	protected static final int MASK_8BITS = 0xff;

	/**
	 * Byte used to pad output.
	 */
	protected static final byte PAD_DEFAULT = '='; // Allow static access to default

	protected final byte PAD = PAD_DEFAULT; // instance variable just in case it needs to vary later

	/**
	 * BASE32 characters are 6 bits in length.
	 * They are formed by taking a block of 3 octets to form a 24-bit string,
	 * which is converted into 4 BASE64 characters.
	 */
	private static final int BITS_PER_ENCODED_BYTE = 6;
	private static final int BYTES_PER_UNENCODED_BLOCK = 3;
	private static final int BYTES_PER_ENCODED_BLOCK = 4;

	/**
	 * Chunk separator per RFC 2045 section 2.1.
	 * <p/>
	 * <p>
	 * N.B. The next major release may break compatibility and make this field private.
	 * </p>
	 *
	 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
	 */
	static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};

	/**
	 * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
	 * equivalents as specified in Table 1 of RFC 2045.
	 * <p/>
	 * Thanks to "commons" project in ws.apache.org for this code.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 */
	private static final byte[] STANDARD_ENCODE_TABLE = {
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
		'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
		'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
		'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
		'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
	};

	/**
	 * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
	 * changed to - and _ to make the encoded Base64 results more URL-SAFE.
	 * This table is only used when the Base64's mode is set to URL-SAFE.
	 */
	private static final byte[] URL_SAFE_ENCODE_TABLE = {
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
		'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
		'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
		'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
		'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
	};

	/**
	 * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
	 * Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
	 * alphabet but fall within the bounds of the array are translated to -1.
	 * <p/>
	 * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
	 * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
	 * <p/>
	 * Thanks to "commons" project in ws.apache.org for this code.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 */
	private static final byte[] DECODE_TABLE = {
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54,
		55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
		5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
		24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
		35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
	};

	/**
	 * Base64 uses 6-bit fields.
	 */
	/**
	 * Mask used to extract 6 bits, used when encoding
	 */
	private static final int MASK_6BITS = 0x3f;

	/**
	 * Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32
	 */
	private final int unencodedBlockSize;

	/**
	 * Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32
	 */
	private final int encodedBlockSize;

	/**
	 * Chunksize for encoding. Not used when decoding.
	 * A value of zero or less implies no chunking of the encoded data.
	 * Rounded down to nearest multiple of encodedBlockSize.
	 */
	protected final int lineLength;

	/**
	 * Size of chunk separator. Not used unless {@link #lineLength} > 0.
	 */
	private final int chunkSeparatorLength;

	/**
	 * Buffer for streaming.
	 */
	protected byte[] buffer;

	/**
	 * Position where next character should be written in the buffer.
	 */
	protected int pos;

	/**
	 * Position where next character should be read from the buffer.
	 */
	private int readPos;

	/**
	 * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless,
	 * and must be thrown away.
	 */
	protected boolean eof;

	/**
	 * Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
	 * make sure each encoded line never goes beyond lineLength (if lineLength > 0).
	 */
	protected int currentLinePos;

	/**
	 * Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding.
	 * This variable helps track that.
	 */
	protected int modulus;

	// The static final fields above are used for the original static byte[] methods on Base64.
	// The private member fields below are used with the new streaming approach, which requires
	// some state be preserved between calls of encode() and decode().

	/**
	 * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
	 * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
	 * between the two modes.
	 */
	private final byte[] encodeTable;

	// Only one decode table currently; keep for consistency with Base32 code
	private final byte[] decodeTable = DECODE_TABLE;

	/**
	 * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
	 */
	private final byte[] lineSeparator;

	/**
	 * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
	 * <code>decodeSize = 3 + lineSeparator.length;</code>
	 */
	private final int decodeSize;

	/**
	 * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
	 * <code>encodeSize = 4 + lineSeparator.length;</code>
	 */
	private final int encodeSize;

	/**
	 * Place holder for the bytes we're dealing with for our based logic.
	 * Bitwise operations store and extract the encoding or decoding from this variable.
	 */
	private int bitWorkArea;

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
	 * <p>
	 * When encoding the line length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p/>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 */
	public Base64() {
		this(0);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
	 * <p>
	 * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p/>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 *
	 * @param urlSafe if <code>true</code>, URL-safe encoding is used. In most cases this should be set to
	 *                <code>false</code>.
	 * @since 1.4
	 */
	public Base64(final boolean urlSafe) {
		this(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
	 * <p>
	 * When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is
	 * STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 *
	 * @param lineLength Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
	 *                   If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
	 * @since 1.4
	 */
	public Base64(final int lineLength) {
		this(lineLength, CHUNK_SEPARATOR);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
	 * <p>
	 * When encoding the line length and line separator are given in the constructor, and the encoding table is
	 * STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 *
	 * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
	 *                      If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
	 * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
	 * @throws IllegalArgumentException Thrown when the provided lineSeparator included some base64 characters.
	 * @since 1.4
	 */
	public Base64(final int lineLength, final byte[] lineSeparator) {
		this(lineLength, lineSeparator, false);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
	 * <p>
	 * When encoding the line length and line separator are given in the constructor, and the encoding table is
	 * STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 *
	 * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
	 *                      If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
	 * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
	 * @param urlSafe       Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
	 *                      operations. Decoding seamlessly handles both modes.
	 * @throws IllegalArgumentException The provided lineSeparator included some base64 characters. That's not going to work!
	 * @since 1.4
	 */
	public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe) {
		unencodedBlockSize = BYTES_PER_UNENCODED_BLOCK;
		encodedBlockSize = BYTES_PER_ENCODED_BLOCK;
		this.lineLength = lineLength;
		chunkSeparatorLength = lineSeparator == null ? 0 : lineSeparator.length;
		// TODO could be simplified if there is no requirement to reject invalid line sep when length <=0
		// @see test case Base64Test.testConstructors()
		if (lineSeparator != null) {
			if (containsAlphabetOrPad(lineSeparator)) {
				final String sep = StringUtil.newStringUtf8(lineSeparator);
				throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
			}
			if (lineLength > 0) { // null line-sep forces no chunking rather than throwing IAE
				encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
				this.lineSeparator = new byte[lineSeparator.length];
				System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
			} else {
				encodeSize = BYTES_PER_ENCODED_BLOCK;
				this.lineSeparator = null;
			}
		} else {
			encodeSize = BYTES_PER_ENCODED_BLOCK;
			this.lineSeparator = null;
		}
		decodeSize = encodeSize - 1;
		encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
	}

	/**
	 * Returns true if this object has buffered data for reading.
	 *
	 * @return true if there is data still available for reading.
	 */
	boolean hasData() {  // package protected for access from I/O streams
		return buffer != null;
	}

	/**
	 * Returns the amount of buffered data available for reading.
	 *
	 * @return The amount of buffered data available for reading.
	 */
	int available() {  // package protected for access from I/O streams
		return buffer != null ? pos - readPos : 0;
	}

	/**
	 * Get the default buffer size. Can be overridden.
	 *
	 * @return {@link #DEFAULT_BUFFER_SIZE}
	 */
	protected int getDefaultBufferSize() {
		return DEFAULT_BUFFER_SIZE;
	}

	/**
	 * Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
	 */
	private void resizeBuffer() {
		if (buffer == null) {
			buffer = new byte[getDefaultBufferSize()];
			pos = 0;
			readPos = 0;
		} else {
			final byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
			System.arraycopy(buffer, 0, b, 0, buffer.length);
			buffer = b;
		}
	}

	/**
	 * Ensure that the buffer has room for <code>size</code> bytes
	 *
	 * @param size minimum spare space required
	 */
	protected void ensureBufferSize(final int size) {
		if (buffer == null || buffer.length < pos + size) {
			resizeBuffer();
		}
	}

	/**
	 * Extracts buffered data into the provided byte[] array, starting at position bPos,
	 * up to a maximum of bAvail bytes. Returns how many bytes were actually extracted.
	 *
	 * @param b      byte[] array to extract the buffered data into.
	 * @param bPos   position in byte[] array to start extraction at.
	 * @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
	 * @return The number of bytes successfully extracted into the provided byte[] array.
	 */
	int readResults(final byte[] b, final int bPos, final int bAvail) {  // package protected for access from I/O streams
		if (buffer != null) {
			final int len = Math.min(available(), bAvail);
			System.arraycopy(buffer, readPos, b, bPos, len);
			readPos += len;
			if (readPos >= pos) {
				buffer = null; // so hasData() will return false, and this method can return -1
			}
			return len;
		}
		return eof ? -1 : 0;
	}

	/**
	 * Checks if a byte value is whitespace or not.
	 * Whitespace is taken to mean: space, tab, CR, LF
	 *
	 * @param byteToCheck the byte to check
	 * @return true if byte is whitespace, false otherwise
	 */
	protected static boolean isWhiteSpace(final byte byteToCheck) {
		switch (byteToCheck) {
		case ' ':
		case '\n':
		case '\r':
		case '\t':
			return true;
		default:
			return false;
		}
	}

	/**
	 * Resets this object to its initial newly constructed state.
	 */
	private void reset() {
		buffer = null;
		pos = 0;
		readPos = 0;
		currentLinePos = 0;
		modulus = 0;
		eof = false;
	}

	/**
	 * Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the
	 * Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
	 *
	 * @param pObject Object to encode
	 * @return An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.
	 * @throws IllegalArgumentException if the parameter supplied is not of type byte[]
	 */
	public Object encode(final Object pObject) {
		if (!(pObject instanceof byte[])) {
			throw new IllegalArgumentException("Parameter supplied to Base-N encode is not a byte[]");
		}
		return encode((byte[]) pObject);
	}

	/**
	 * Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet.
	 *
	 * @param pArray a byte array containing binary data
	 * @return A String containing only Base-N character data
	 */
	public String encodeToString(final byte[] pArray) {
		return StringUtil.newStringUtf8(encode(pArray));
	}

	/**
	 * Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the
	 * Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
	 *
	 * @param pObject Object to decode
	 * @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String supplied.
	 * @throws IllegalArgumentException if the parameter supplied is not of type byte[]
	 */
	public Object decode(final Object pObject) throws IllegalArgumentException {
		if (pObject instanceof byte[]) {
			return decode((byte[]) pObject);
		} else if (pObject instanceof String) {
			return decode((String) pObject);
		} else {
			throw new IllegalArgumentException("Parameter supplied to Base-N decode is not a byte[] or a String");
		}
	}

	/**
	 * Decodes a String containing characters in the Base-N alphabet.
	 *
	 * @param pArray A String containing Base-N character data
	 * @return a byte array containing binary data
	 */
	public byte[] decode(final String pArray) {
		return decode(StringUtil.getBytesUtf8(pArray));
	}

	/**
	 * Decodes a byte[] containing characters in the Base-N alphabet.
	 *
	 * @param pArray A byte array containing Base-N character data
	 * @return a byte array containing binary data
	 */
	public byte[] decode(final byte[] pArray) {
		reset();
		if (pArray == null || pArray.length == 0) {
			return pArray;
		}
		decode(pArray, 0, pArray.length);
		decode(pArray, 0, -1); // Notify decoder of EOF.
		final byte[] result = new byte[pos];
		readResults(result, 0, result.length);
		return result;
	}

	/**
	 * Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
	 *
	 * @param pArray a byte array containing binary data
	 * @return A byte array containing only the basen alphabetic character data
	 */
	public byte[] encode(final byte[] pArray) {
		reset();
		if (pArray == null || pArray.length == 0) {
			return pArray;
		}
		encode(pArray, 0, pArray.length);
		encode(pArray, 0, -1); // Notify encoder of EOF.
		final byte[] buf = new byte[pos - readPos];
		readResults(buf, 0, buf.length);
		return buf;
	}

	/**
	 * Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
	 * Uses UTF8 encoding.
	 *
	 * @param pArray a byte array containing binary data
	 * @return String containing only character data in the appropriate alphabet.
	 */
	public String encodeAsString(final byte[] pArray) {
		return StringUtil.newStringUtf8(encode(pArray));
	}

	/**
	 * Returns whether or not the <code>octet</code> is in the current alphabet.
	 * Does not allow whitespace or pad.
	 *
	 * @param octet The value to test
	 * @return <code>true</code> if the value is defined in the current alphabet, <code>false</code> otherwise.
	 */
	protected boolean isInAlphabet(final byte octet) {
		return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
	}

	/**
	 * Tests a given byte array to see if it contains only valid characters within the alphabet.
	 * The method optionally treats whitespace and pad as valid.
	 *
	 * @param arrayOctet byte array to test
	 * @param allowWSPad if <code>true</code>, then whitespace and PAD are also allowed
	 * @return <code>true</code> if all bytes are valid characters in the alphabet or if the byte array is empty;
	 *         <code>false</code>, otherwise
	 */
	public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
		for (int i = 0; i < arrayOctet.length; i++) {
			if (!isInAlphabet(arrayOctet[i]) &&
					(!allowWSPad || arrayOctet[i] != PAD && !isWhiteSpace(arrayOctet[i]))) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Tests a given String to see if it contains only valid characters within the alphabet.
	 * The method treats whitespace and PAD as valid.
	 *
	 * @param basen String to test
	 * @return <code>true</code> if all characters in the String are valid characters in the alphabet or if
	 *         the String is empty; <code>false</code>, otherwise
	 * @see #isInAlphabet(byte[], boolean)
	 */
	public boolean isInAlphabet(final String basen) {
		return isInAlphabet(StringUtil.getBytesUtf8(basen), true);
	}

	/**
	 * Tests a given byte array to see if it contains any characters within the alphabet or PAD.
	 * <p/>
	 * Intended for use in checking line-ending arrays
	 *
	 * @param arrayOctet byte array to test
	 * @return <code>true</code> if any byte is a valid character in the alphabet or PAD; <code>false</code> otherwise
	 */
	protected boolean containsAlphabetOrPad(final byte[] arrayOctet) {
		if (arrayOctet == null) {
			return false;
		}
		for (final byte element : arrayOctet) {
			if (PAD == element || isInAlphabet(element)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Calculates the amount of space needed to encode the supplied array.
	 *
	 * @param pArray byte[] array which will later be encoded
	 * @return amount of space needed to encoded the supplied array.
	 *         Returns a long since a max-len array will require > Integer.MAX_VALUE
	 */
	public long getEncodedLength(final byte[] pArray) {
		// Calculate non-chunked size - rounded up to allow for padding
		// cast to long is needed to avoid possibility of overflow
		long len = (pArray.length + unencodedBlockSize - 1) / unencodedBlockSize * (long) encodedBlockSize;
		if (lineLength > 0) { // We're using chunking
			// Round up to nearest multiple
			len += (len + lineLength - 1) / lineLength * chunkSeparatorLength;
		}
		return len;
	}

	/**
	 * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
	 *
	 * @return true if we're in URL-SAFE mode, false otherwise.
	 * @since 1.4
	 */
	public boolean isUrlSafe() {
		return encodeTable == URL_SAFE_ENCODE_TABLE;
	}

	/**
	 * <p>
	 * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
	 * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
	 * remaining bytes (if not multiple of 3).
	 * </p>
	 * <p>
	 * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 * </p>
	 *
	 * @param in      byte[] array of binary data to base64 encode.
	 * @param inPos   Position to start reading data from.
	 * @param inAvail Amount of bytes available from input for encoding.
	 */
	void encode(final byte[] in, int inPos, final int inAvail) {
		if (eof) {
			return;
		}
		// inAvail < 0 is how we're informed of EOF in the underlying data we're
		// encoding.
		if (inAvail < 0) {
			eof = true;
			if (0 == modulus && lineLength == 0) {
				return; // no leftovers to process and not using chunking
			}
			ensureBufferSize(encodeSize);
			final int savedPos = pos;
			switch (modulus) { // 0-2
			case 1: // 8 bits = 6 + 2
				buffer[pos++] = encodeTable[bitWorkArea >> 2 & MASK_6BITS]; // top 6 bits
				buffer[pos++] = encodeTable[bitWorkArea << 4 & MASK_6BITS]; // remaining 2
				// URL-SAFE skips the padding to further reduce size.
				if (encodeTable == STANDARD_ENCODE_TABLE) {
					buffer[pos++] = PAD;
					buffer[pos++] = PAD;
				}
				break;

			case 2: // 16 bits = 6 + 6 + 4
				buffer[pos++] = encodeTable[bitWorkArea >> 10 & MASK_6BITS];
				buffer[pos++] = encodeTable[bitWorkArea >> 4 & MASK_6BITS];
				buffer[pos++] = encodeTable[bitWorkArea << 2 & MASK_6BITS];
				// URL-SAFE skips the padding to further reduce size.
				if (encodeTable == STANDARD_ENCODE_TABLE) {
					buffer[pos++] = PAD;
				}
				break;
			}
			currentLinePos += pos - savedPos; // keep track of current line position
			// if currentPos == 0 we are at the start of a line, so don't add CRLF
			if (lineLength > 0 && currentLinePos > 0) {
				System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
				pos += lineSeparator.length;
			}
		} else {
			for (int i = 0; i < inAvail; i++) {
				ensureBufferSize(encodeSize);
				modulus = (modulus + 1) % BYTES_PER_UNENCODED_BLOCK;
				int b = in[inPos++];
				if (b < 0) {
					b += 256;
				}
				bitWorkArea = (bitWorkArea << 8) + b; //  BITS_PER_BYTE
				if (0 == modulus) { // 3 bytes = 24 bits = 4 * 6 bits to extract
					buffer[pos++] = encodeTable[bitWorkArea >> 18 & MASK_6BITS];
					buffer[pos++] = encodeTable[bitWorkArea >> 12 & MASK_6BITS];
					buffer[pos++] = encodeTable[bitWorkArea >> 6 & MASK_6BITS];
					buffer[pos++] = encodeTable[bitWorkArea & MASK_6BITS];
					currentLinePos += BYTES_PER_ENCODED_BLOCK;
					if (lineLength > 0 && lineLength <= currentLinePos) {
						System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
						pos += lineSeparator.length;
						currentLinePos = 0;
					}
				}
			}
		}
	}

	/**
	 * <p>
	 * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
	 * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
	 * call is not necessary when decoding, but it doesn't hurt, either.
	 * </p>
	 * <p>
	 * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
	 * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
	 * garbage-out philosophy: it will not check the provided data for validity.
	 * </p>
	 * <p>
	 * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 * </p>
	 *
	 * @param in      byte[] array of ascii data to base64 decode.
	 * @param inPos   Position to start reading data from.
	 * @param inAvail Amount of bytes available from input for encoding.
	 */
	void decode(final byte[] in, int inPos, final int inAvail) {
		if (eof) {
			return;
		}
		if (inAvail < 0) {
			eof = true;
		}
		for (int i = 0; i < inAvail; i++) {
			ensureBufferSize(decodeSize);
			final byte b = in[inPos++];
			if (b == PAD) {
				// We're done.
				eof = true;
				break;
			} else {
				if (b >= 0 && b < DECODE_TABLE.length) {
					final int result = DECODE_TABLE[b];
					if (result >= 0) {
						modulus = (modulus + 1) % BYTES_PER_ENCODED_BLOCK;
						bitWorkArea = (bitWorkArea << BITS_PER_ENCODED_BYTE) + result;
						if (modulus == 0) {
							buffer[pos++] = (byte) (bitWorkArea >> 16 & MASK_8BITS);
							buffer[pos++] = (byte) (bitWorkArea >> 8 & MASK_8BITS);
							buffer[pos++] = (byte) (bitWorkArea & MASK_8BITS);
						}
					}
				}
			}
		}

		// Two forms of EOF as far as base64 decoder is concerned: actual
		// EOF (-1) and first time '=' character is encountered in stream.
		// This approach makes the '=' padding characters completely optional.
		if (eof && modulus != 0) {
			ensureBufferSize(decodeSize);

			// We have some spare bits remaining
			// Output all whole multiples of 8 bits and ignore the rest
			switch (modulus) {
			//   case 1: // 6 bits - ignore entirely
			//       break;
			case 2: // 12 bits = 8 + 4
				bitWorkArea = bitWorkArea >> 4; // dump the extra 4 bits
				buffer[pos++] = (byte) (bitWorkArea & MASK_8BITS);
				break;
			case 3: // 18 bits = 8 + 8 + 2
				bitWorkArea = bitWorkArea >> 2; // dump 2 bits
				buffer[pos++] = (byte) (bitWorkArea >> 8 & MASK_8BITS);
				buffer[pos++] = (byte) (bitWorkArea & MASK_8BITS);
				break;
			}
		}
	}

	/**
	 * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
	 *
	 * @param octet The value to test
	 * @return <code>true</code> if the value is defined in the the base 64 alphabet, <code>false</code> otherwise.
	 * @since 1.4
	 */
	public static boolean isBase64(final byte octet) {
		return octet == PAD_DEFAULT || octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1;
	}

	/**
	 * Tests a given String to see if it contains only valid characters within the Base64 alphabet. Currently the
	 * method treats whitespace as valid.
	 *
	 * @param base64 String to test
	 * @return <code>true</code> if all characters in the String are valid characters in the Base64 alphabet or if
	 *         the String is empty; <code>false</code>, otherwise
	 * @since 1.5
	 */
	public static boolean isBase64(final String base64) {
		return isBase64(StringUtil.getBytesUtf8(base64));
	}

	/**
	 * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
	 * method treats whitespace as valid.
	 *
	 * @param arrayOctet byte array to test
	 * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
	 *         <code>false</code>, otherwise
	 * @since 1.5
	 */
	public static boolean isBase64(final byte[] arrayOctet) {
		for (int i = 0; i < arrayOctet.length; i++) {
			if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Encodes binary data using the base64 algorithm but does not chunk the output.
	 *
	 * @param binaryData binary data to encode
	 * @return byte[] containing Base64 characters in their UTF-8 representation.
	 */
	public static byte[] encodeBase64(final byte[] binaryData) {
		return encodeBase64(binaryData, false);
	}

	/**
	 * Encodes binary data using the base64 algorithm but does not chunk the output.
	 * <p/>
	 * NOTE:  We changed the behaviour of this method from multi-line chunking (commons-codec-1.4) to
	 * single-line non-chunking (commons-codec-1.5).
	 *
	 * @param binaryData binary data to encode
	 * @return String containing Base64 characters.
	 * @since 1.4 (NOTE:  1.4 chunked the output, whereas 1.5 does not).
	 */
	public static String encodeBase64String(final byte[] binaryData) {
		return StringUtil.newStringUtf8(encodeBase64(binaryData, false));
	}

	/**
	 * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
	 * url-safe variation emits - and _ instead of + and / characters.
	 *
	 * @param binaryData binary data to encode
	 * @return byte[] containing Base64 characters in their UTF-8 representation.
	 * @since 1.4
	 */
	public static byte[] encodeBase64URLSafe(final byte[] binaryData) {
		return encodeBase64(binaryData, false, true);
	}

	/**
	 * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
	 * url-safe variation emits - and _ instead of + and / characters.
	 *
	 * @param binaryData binary data to encode
	 * @return String containing Base64 characters
	 * @since 1.4
	 */
	public static String encodeBase64URLSafeString(final byte[] binaryData) {
		return StringUtil.newStringUtf8(encodeBase64(binaryData, false, true));
	}

	/**
	 * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
	 *
	 * @param binaryData binary data to encode
	 * @return Base64 characters chunked in 76 character blocks
	 */
	public static byte[] encodeBase64Chunked(final byte[] binaryData) {
		return encodeBase64(binaryData, true);
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
	 *
	 * @param binaryData Array containing binary data to encode.
	 * @param isChunked  if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
	 */
	public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked) {
		return encodeBase64(binaryData, isChunked, false);
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
	 *
	 * @param binaryData Array containing binary data to encode.
	 * @param isChunked  if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
	 * @param urlSafe    if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
	 * @since 1.4
	 */
	public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe) {
		return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
	 *
	 * @param binaryData    Array containing binary data to encode.
	 * @param isChunked     if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
	 * @param urlSafe       if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
	 * @param maxResultSize The maximum result size to accept.
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than maxResultSize
	 * @since 1.4
	 */
	public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe, final int maxResultSize) {
		if (binaryData == null || binaryData.length == 0) {
			return binaryData;
		}

		// Create this so can use the super-class method
		// Also ensures that the same roundings are performed by the ctor and the code
		final Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
		final long len = b64.getEncodedLength(binaryData);
		if (len > maxResultSize) {
			throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
					len +
					") than the specified maximum size of " +
					maxResultSize);
		}

		return b64.encode(binaryData);
	}

	/**
	 * Decodes a Base64 String into octets
	 *
	 * @param base64String String containing Base64 data
	 * @return Array containing decoded data.
	 * @since 1.4
	 */
	public static byte[] decodeBase64(final String base64String) {
		return new Base64().decode(base64String);
	}

	/**
	 * Decodes Base64 data into octets
	 *
	 * @param base64Data Byte array containing Base64 data
	 * @return Array containing decoded data.
	 */
	public static byte[] decodeBase64(final byte[] base64Data) {
		return new Base64().decode(base64Data);
	}

	// Implementation of the Encoder Interface

	// Implementation of integer encoding used for crypto

	/**
	 * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
	 *
	 * @param pArray a byte array containing base64 character data
	 * @return A BigInteger
	 * @since 1.4
	 */
	public static BigInteger decodeInteger(final byte[] pArray) {
		return new BigInteger(1, decodeBase64(pArray));
	}

	/**
	 * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
	 *
	 * @param bigInt a BigInteger
	 * @return A byte array containing base64 character data
	 * @throws NullPointerException if null is passed in
	 * @since 1.4
	 */
	public static byte[] encodeInteger(final BigInteger bigInt) {
		if (bigInt == null) {
			throw new NullPointerException("encodeInteger called with null parameter");
		}
		return encodeBase64(toIntegerBytes(bigInt), false);
	}

	/**
	 * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
	 *
	 * @param bigInt <code>BigInteger</code> to be converted
	 * @return a byte array representation of the BigInteger parameter
	 */
	static byte[] toIntegerBytes(final BigInteger bigInt) {
		int bitlen = bigInt.bitLength();
		// round bitlen
		bitlen = bitlen + 7 >> 3 << 3;
		final byte[] bigBytes = bigInt.toByteArray();

		if (bigInt.bitLength() % 8 != 0 && bigInt.bitLength() / 8 + 1 == bitlen / 8) {
			return bigBytes;
		}
		// set up params for copying everything but sign bit
		int startSrc = 0;
		int len = bigBytes.length;

		// if bigInt is exactly byte-aligned, just skip signbit in copy
		if (bigInt.bitLength() % 8 == 0) {
			startSrc = 1;
			len--;
		}
		final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
		final byte[] resizedBytes = new byte[bitlen / 8];
		System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
		return resizedBytes;
	}

}